The document discusses various hormones and how they regulate biological processes in the body. It describes how hormones are chemical messengers that are produced by endocrine glands and circulated in the bloodstream to target cells. Key hormones discussed include those produced by the hypothalamus, pituitary gland, thyroid gland, adrenal cortex, reproductive organs, and those involved in calcium and phosphate homeostasis such as calcitriol, calcitonin, and parathyroid hormone. The effects and regulatory mechanisms of these hormones are summarized.

1. Biochemistry
for
PBBN
HORMONE
BRAINSTROMING NOTESTO PRINT

2. The Fact
 Living body possesses a remarkable
communication system to coordinate its
biological functions.
 The nervous system coordinates the body
function through the transmission of
electro chemical impulses.
 The endocrine system acts through wide
ranges of chemical messengers
known as hormones.

3. Hormone
Hormones are defined as organic
substances, produced in small amounts
by specific tissues (endocrine glands),
secreted into the blood stream to
control the metabolic and biological
activities in the target cells.

4. Hormone
 Chemical messengers involved in the
transmission of information from one tissue to
another and from cell to cell.
 Hormones are secreted by specialized endocrine
glands/tissues.
 Endocrine: ductless, and secreted straight into the
blood
 Exocrine: with ducts

5. Sources of Hormones
Hypothalamus TRH, CRH, GHRH, GHIH, GnRH, PIF (Prolactine
Inhibiting Factor)
Ant Pituitary GH, TSH, ACTH, Prolactin, FSH, LH
Post Pituitary Oxytocin, ADH
Thyroid T3, T4, Calcitonin
Adrenal Cortex Cortisol, Aldosterone
Adrenal Medulla Epinephrine, Norepinephrine
Pancreas Insulin, Glucagon
Parathyroid PTH
Testes Testosterone
Ovary Oestrogen, Progesterone

6. Sources of Hormones
Placenta HCG, Human Somatomammotropin, Oestrogen,
Progesterone
Kidney Renin, Erythropoeitin, 1,25-Dihydroxycholecalciferol
Heart ANP (Arterial Natriuretic Peptide)
Stomach Gastrin
Small Intestine Secretin, CCK (Cholecystokinin)
Adipocytes Leptin

7. Classification
Classified in many ways based on their
characteristics and functions
 Based on the chemical nature
 Based on the mechanism of action
 Group I Hormones:
 Group II Hormones:
 The second messenger is cAMP
 The second messenger is Phosphatidyl inositol / calcium
 The second messenger is unknown

8. Classification
Classified in many ways based on their
characteristics and functions
 Based on the chemical nature
 Protein or Peptide Hormones: e.g. Insulin, glucagon,
antidiuretics, oxytocin hormons.
 Steroid Hormones: e.g. Glucocorticoides,
Mineralocorticoides, Sex hormones
 Amino acid derivatives: e.g. Epinephrine,
norepinephrine, thyroxin, triiodothyroxinine.

9. Classification
 Based on the mechanism of action
 Group I Hormones: Bind to intracellular receptors to form
receptor-hormone complexes through which their
biochemical functions are mediated. e.g. Estrogens,
androgens, glucocorticoids, calcitriol,T3,T4.
 Group II Hormones: Bind to cell surface receptors and
stimulates the release of certain molecules, namely the
second messengers which in turn, performs the
biochemical functions.
 The second messenger is cAMP e.g. ACTH, FSH, LH, PTH,
Glucagon, Calcitonin
 The second messenger is Phosphatidyl inositol / calcium e.g
TRH, GnRH, Gastrin, CCK.
 The second messenger is unknown e.g. Growth hormone,
Insulin, Oxytocin, Prolactin.

10. Functions of Hormones
 Growth & Development
 Reproduction (both male & female have
receptors for both male & female hormones)
 Production, Utilization, Energy Storage
 Maintain internal environment of the body

11. Mode of Action of Group-I Hormone
Hormones are lipophilic in nature
Can easily pass across the plasma membrane
Acts through intracellular receptors (in cytosol/nucleous)
Hormone complex receptor bind to the specific region of
the DNA
Called
Hormone Responsive Element (HRE)
Causes
Increased expression of specific genes
Promotes
Elongation & termination of RNA synthesis
(transcription)
Production of specific protein in response to hormonal
action.

12. Mode of Action of Group-II Hormone
Hormones are considered as the first messenger
Exert their action through secondary messenger.
 cAMP
 Phosphatidyl insitol / Calcium
 Unknown

13. Clinical Significance of Thyroid
Hormone
 Thyroid disorders include
 HYPERTHYROIDISM (ABNORMALLY INCREASED ACTIVITY),
 HYPOTHYROIDISM (ABNORMALLY DECREASED ACTIVITY)
 THYROIDITIS (INFLAMMATION OF THE THYROID)
 THYROID NODULES, (WHICH ARE GENERALLY BENIGN
THYROID NEOPLASM (TUMOURS), BUT MAY BE THYROID
CANCERS).

14. Hyperthyroidism
 Overproduction of the thyroid hormonesT3 andT4
 Graves' disease, an autoimmune disease (anomalous
antibodies stimulate the thyroid to secrete excessive
quantities of thyroid hormones)
 Lack of negative feedback mechanisms leads to toxic
goiter.
 Symptoms such as a thyroid goiter, protruding eyes
(exopthalmos), palpitations, excess sweating,
diarrhea, weight loss, muscle weakness and unusual
sensitivity to heat

15. Hypothyroidism
 Hypothyroidism is the underproduction of the
thyroid hormonesT3 andT4.

 Hypothyroid disorders may occur as a result of
 Congenital thyroid abnormalities
 Autoimmune disorders such as Hashimoto's
thyroiditis,
 Iodine deficiency (more likely in poorer countries) or
 The removal of the thyroid following surgery to
treat severe hyperthyroidism and/or thyroid cancer.

16. Thyroiditis
 The overproduction of T3 and T4 followed by
the underproduction of T3 and T4). These are
Hashimoto's thyroiditis and postpartum
thyroiditis.
 Cancers
 Non-cancerous nodules

17. Hormones of Adrenal Cortex
 Mineralocorticoids
 Glucocorticoids
 Androgens

18. Mineralocorticoides
 Produced by adrenocortical zona
glomerulosa
 Aldosterone is largely responsible for the
long-term regulation of blood pressure
 Distal convoluted tubule and collecting duct
of the kidney where it causes increased
reabsorption of sodium and increased
excretion of both potassium and hydrogen
ions

19. Glucocorticoides
 produced in the zona fasciculata
 ACTH regulates the secretion of lucocorticoides.
 Cortisol enhances metabolism in several ways:
 (+) release of amino acids from the body
 (+) lipolysis, the breakdown of fat
 (+) gluconeogenesis
 It increases blood glucose levels in response to stress,
by inhibiting glucose uptake into muscle and fat cells
 It strengthens cardiac muscle contractions
 It increases water retention
 It has anti-inflammatory and anti-allergic effects

20. Androgens
 Produced in the zona reticularis.
 Testosterone:
 Dihydrotestosterone

21. Hormones of Reproductive System
 Females
 The ovaries of sexually-mature females
secrete:
 Estrogens
 Progesterone
 Males
 Testosterone.

22. Estrogens
 Responsible for the conversion of girls into
sexually-mature women.
 Development of breasts
 Further development of the uterus and vagina
 Broadening of the pelvis
 Growth of pubic and axillary hair
 Increase in adipose (fat) tissue
 Participate in the monthly preparation of the body for a
possible pregnancy
 Participate in pregnancy if it occurs

23. Progesterone
 It has many effects in the body,
 Some having nothing to do with sex and
reproduction.
 Role in the menstrual cycle and pregnancy.

24. Regulation of Estrogen and
Progesterone
Hypothalamus → GnRH → Pituitary→
FSH→ Follicle→ Estrogens

25.  Hypothalamus → GnRH→ Pituitary→
LH→ Corpus luteum→ Progesterone

26. Calcium Phosphate Homeostasis
 The hormones calcitriol, calcitonin and
parathyroid regulate body calcium
 PTH and calcitriol also regulate
phosphate in the body

27. Regulation of Calcium
 Decreased Calcium Level in blood.
 Kidney Produce Calcitriol (A form ofVit. D)
 Increase the Uptake of calcium from food and
release calcium forom bones.
 PTH increase the Ca level in blood by stimulating
bone to release calcium & reabsorption of
calcium from urine, absorption of Ca from
intestine.
 Calcitonin, decrease the blood Ca level. (feedback
mechanism) (Inhibit abosorption, reabsorption
and release of calcium form Intestine, Kidney and
Bones respectively.)

28. Phosphate Regulation
 PTH helps lower blood phosphate levels.
 PTH reduce the reabsorption of phosphates
dissolved in urine.
 Causing more excretion of phosphates.
 Calcitriol raises the level of phosphate in the
blood by promoting its absorption by the
intestine. (Feedback mechanism).

29. Calcium Phosphate
Homeostasis